The Co3Pt magnetic layer with thickness of 7~28 nm was deposited onto the Pt underlayer. The as-deposited Co3Pt/Pt double-layered films with or without a 5 nm Pt capped layer were annealed at temperatures between 275 and 375 °C in vacuum of 1 mTorr. The influences of process parameters on perpendicular magnetic properties of Co3Pt thin films were investigated. The Co3Pt film with perpendicular coercivity (Hc⊥) value of 3620 Oe and the perpendicular squareness (S⊥) of 0.7 could be achieved from the Co3Pt(18 nm)/Pt(100 nm) double-layered films by annealing at 300°C. Further added Tb30Co70 film on the Co3Pt/Pt double-layered film could greatly enhance the perpendicular magnetic properties of the film. The Hc⊥ and S⊥ of the Tb30Co70/Co3Pt/Pt film were as high as 6560 Oe and 0.88, respectively, which has significant potential to be applied in perpendicular magnetic recording media.